Magnetic anisotropy of Fe, Mn and Ni substituted Er2Co17ternaries

The saturation magnetization, Curie temperature, easy direction of magnetization and anisotropy field of Er
2
Co
17-x
M
x
compounds where M = Fe, Mn or Ni were investigated. It was not possible to prepare single phase materials for x > 6 when M = Mn and for x > 10 when M = Ni. The Mn containing ternaries possess an easy direction of magnetization along the c-axis whereas for Fe containing ternaries the easy direction changes from c-axis to basal plane for x > 10. In the case of Er
2
Co
17-x
Ni
x
the easy direction changes from c-axis to basal plane with nickel substitution and the remains along the basal plane until x = 8 at which concentration the spins prefer the c-axis. At low temperatures Er
2
Fe
11
Co
6
, Er
2
Co
15
Ni
2
, and Er
2
Co
11
Co
6
show a tendency to deviate from the easy plane. The Curie temperature decreases with M substitution and the decrease is rapid when M = Mn. Er
2
Co
15
Mn
2
possess an anisotropy field of 133 kOe at 4.2 K as compared to 31 kOe for Er
2
Co
17
Ni. A model is proposed to explain the easy axis change as a function of M.